WAEC - Mathematics (2015 - No. 30)
In the given diagram, \(\bar{QT}\) and \(\bar{PR}\) are straight lines, < ROS = (3n - 20), < SOT = n, < POL = m and < QOL is a right angle. Find the value of n.
35o
40o
55o
60o
설명
In the diagram, QOR + 2m(vertically opposite angles)
So, m + 90° + 2m = 180°
(angles on str. line)
3m = 180° - 90°
3m = 90°
m = \(\frac{90^o}{3}\)
= 30°
substituting 30° for m in
2m + 4n = 200° gives
2 x 30° + 4n = 200°
60° + 4n = 200°
4n = 200° - 60°
= 140°
n = \(\frac{140°}{4}\)
= 35°
So, m + 90° + 2m = 180°
(angles on str. line)
3m = 180° - 90°
3m = 90°
m = \(\frac{90^o}{3}\)
= 30°
substituting 30° for m in
2m + 4n = 200° gives
2 x 30° + 4n = 200°
60° + 4n = 200°
4n = 200° - 60°
= 140°
n = \(\frac{140°}{4}\)
= 35°